To provide an encoding device capable of encoding even a signal which principally consists of a speech and on which music and an environmental sound are superposed at a low bit rate with high quality.

A down samplers 101 decreases the sampling rate of an input signal from a sampling rate FH to a sampling rate FL. A basic layer encoder 102 encodes a sound signal with the sampling rate FL. A local decoder 103 decodes the encoded code outputted from the basic laser encoder 102. An up sampler 104 increases the sampling rate of the decoded signal to the sampling rate FH. A subtractor 106 subtracts the decoded signal from the sound signal with the sampling rate FH. An extended layer encoder 107 encodes the signal outputted from the subtractor 106 by using parameters of the decoding result outputted from the local decoder 103.

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